The present invention relates to a technology for drying a substrate and more particularly to a technology for drying a substrate using an air knife.
Conventionally, in a manufacturing process of a liquid crystal device, a color filter, a photo-mask and so forth, such a kind of substrate drying method is used for drying a rectangular shaped substrate of which surface has been treated in a wet manner of every kind such as a substrate cleaning treatment, and is applied to work for removing droplets attached to the rectangular shaped substrate and drying the substrate.
As a liquid cutting device for removing droplets attached to a rectangular shaped substrate, for example, the device described in JP-A-338686-1996 and the device described in JP-A-302779-1995 are known. The conventional example described in JP-A-302779-1995 will be explained based on FIG. 7 and FIG. 8.
The conventional device shown in FIG. 7 and FIG. 8 comprises a carriage mechanism 110 for horizontally carrying a rectangular shaped substrate W, a first gas injection mechanism 120 for jetting a gas toward both upper and lower surfaces of the rectangular shaped substrate W being carried, and a second gas injection mechanism 130 for jetting a gas toward both upper and lower surfaces of the rectangular shaped substrate W backward from the first gas injection mechanism 120.
Up-and-down air knives 121 of the first gas injection mechanism 120 are placed so that the knife has a slant to a direction orthogonal to a direction of the carriage, and each up-and-down air knife 131 of the second gas injection mechanism 130 is placed so that the knife has a slant in a direction opposite to a direction of that of each up-and-down air knife 121 of the first gas injection mechanism 120 and is constructed so as to finally remove droplets by the second gas injection mechanism 130, which have remained at a corner portion of the rectangular shaped substrate W without being blown away by the first gas injection mechanism 120.
An arrangement of the conventional drying method comprises, as shown in FIG. 8, the first gas injection mechanism 120 and the second gas injection mechanism 130. A condition of removing droplets of the rectangular shaped substrate W is shown in FIG. 9. In order to facilitate to remove the droplets (shown by oblique lines in FIG. 9) of the rectangular shaped substrates W, each gas injection mechanism is placed so as to be in the shape of a Japanese letter in a horizontal plane and so as to have a slant to a direction orthogonal to a carriage direction of the rectangular shaped substrate W. At first, the droplets that have been swept away and remained at a corner portion of the rectangular shaped substrate W by the first gas injection mechanism 120 remains at a corner portion X of the rectangular shaped substrate W. The remaining droplets are removed in a manner that liquid X at the corner portion of the rectangular shaped substrate that has not been removed by the first injection mechanism is blown away while being swept along an end surface of the substrate from the corner portion of the rectangular shaped substrate by the second gas injection mechanism 130. Regardless of the arrangement in which the droplets attached to the surface of the substrate is completely removed, the droplets X that has been driven into the corner portion of the substrate W are not completely removed and remain stained (as a local thin film) since, in case of some kinds of a substrate, the droplets are not blown away from the end surfaces of the substrate and an attachment force to the rectangular shaped substrate W is increased.
Also, the droplets X that have been swept away once by the first injection mechanism follow the substrate end surfaces of the rectangular shaped substrate W, and by following the substrate end surfaces by means of the second gas injection mechanism again, the droplets swallow up particles of the substrate end surfaces to form a stain. Then, the stain peels during a manufacturing process and becomes the cause of particles or is a hindrance to making an element on the substrate. Also, since it is necessary to set two air knives, an area for setting becomes to be large. In fabricating a device, a cost of the device also goes up. Further, since an amount of use of an air being supplied to the two air knives becomes to be twice compared with the conventional case of one air knife, a cost of required power becomes to be twice.